Arsenic in rice production study

Dustin Harrell, LSU Agcenter agronomist at the Rice Research Station here, is participating in a multistate study on arsenic in rice to determine if levels of the element are higher in different varieties and to see if varied flooding methods affect arsenic content.

“Can we change the water management practices to alter the uptake and accumulation of arsenic in rice? That’s what we are investigating,” Harrell said.

All plants naturally absorb arsenic from the soil, but rice tends to absorb more because it is growing in a flooded, anaerobic condition. This makes arsenic more available for uptake by the plant, he said.

The different flooding regimes being used include:

– The traditional drill-seeded, delayed-flood management practice, where a flood is applied after the rice reaches the three-to-four-leaf stage of development and is left until two weeks before harvest.

– Intermittent flooding, where the initial flood is held for two to three weeks, then allowing the flood to evaporate until mud is exposed, followed by pumping water to a 2-4-inch depth.

– Semi-aerobic rice management, where flushing is conducted regularly, but aerobic conditions are allowed to persist.

– Straight-head management, where the rice is flooded for 10 days to two weeks followed by draining until the soil cracks, followed by re-flooding until draining for harvest.

The testing is being conducted in all rice-growing states, including Texas, California, Mississippi, Arkansas, Missouri and Louisiana.

Harrell said the flooding practices that allow the field to drain will require more weed management, which will increase herbicide expenses and disease pressure and reduce grain yield.

Varieties being tested are CL151, Cheniere, Presidio and Jupiter – along with hybrids CLXL729 and CLXL745.

Harrell said all rice samples will be milled at the Rice Research Station and then sent to a lab for determining inorganic and organic arsenic content. He said results should be available by the spring of 2014.

The U.S. Food and Drug Administration has recently reported the results of testing and concluded that there are no health issues associated with arsenic in rice and rice products.

“This study is simply long-term research to allow Louisiana rice producers to produce the safest, most nutritious rice available for our customers,” said Steve Linscombe, director of the Rice Research Station.